Duplo can be ridiculously expensive. If you're not careful, you'll can easily spend up to £1 per piece!
Our selections here try and balance price with playability, picking sets that either offer a lot of blocks for only a little money, or present good scenarios like cars and houses which all young children will understand. The exception to this is the Deluxe Train, which has a silly price, but young children will adore it.
Sets with lots of people and animals are normally a good idea, but we would also recommend avoiding the branded sets (Spiderman, Disney etc) as these are often the most expensive, and most 1-2 years olds probably won't care anyway.